L2 Ch-2 Sol Biomolecules - 1 File Download

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SECTION - A

Objective Type Questions

(How to analyse chemical composition? Primary and secondary metabolites, carbohydrates)

1. In maltose, glycosidic bond is formed between

(1) Carbon 1 of one glucose molecule and carbon 4 of second glucose molecule




Sol. Answer (1)

H

OH

H

CH OH2

H

OH

H

H

OH

O

1

H

O

H

CH OH2

H

OH

H

H

OH

O

4

OH

2. The given structure represents a monosaccharide known as

O

OH OH

HOCH2

OH OH

(1) Ribose (2) Glucose (3) Fructose (4) Raffinose

Sol. Answer (1)

Ribose is a pentose sugar.

3. Chitin present in the exoskeletons of arthropods is

(1) Protein (2) Homopolysaccharide (3) Lipid (4) Derived monosaccharide

Sol. Answer (2)

Chitin is a polymer of nitrogen containing glucose derivative known as N-acetyl glucosamine (NAG).

Chapter 2

Biomolecules

Solutions

Level - II

56 Biomolecules Solutions of Assignment (Level-II)


4. One of the following is correct sequence of carbohydrates in the order of increasing complexity of chemicalstructure

(1) Sucrose, starch, oligosaccharide, maltose, triose (2) Triose, chitin, sucrose, oligosaccharide, starch

(3) Triose, glucose, maltose, oligosaccharide, starch (4) Oligosaccharide, triose, starch, sucrose, maltose

Sol. Answer (3)

Triose – 3 C containing molecule

Glucose – monosaccharide (6 C)

Maltose – Disaccharide (2 monosaccharide units)

Sucrose – Disaccharide (2 monosaccharide units)

Oligosaccharide – (2–10) monosaccharide units

Starch – Polysaccharide

Chitin – Polysaccharide

5. Glucose is stored as glycogen in

(1) Pancreas (2) Bone (3) Kidney (4) Liver

Sol. Answer (4)

Because liver is a gland where glucose get converted into glycogen.

6. Which of the following is one of the sweetest protein obtained from African berry plant?

(1) Monellin (2) Resilin (3) Collagen (4) GLUT-4

Sol. Answer (1)

Monellin is the sweetest protein obtained from African berry plant. Resilin is elastic material formed of protein

chains and found in insect cuticles.

7. Both in cells and extracellular fluids diabasic phosphate (HPO )--

4and monobasic phosphate (H PO )-

2 4 act as

acid base buffers to maintain

(1) K+ concentration of extracellular fluid (2) Na+ concentration of extracellular fluid

(3) Na+ concentration of cellular fluid (4) H+ concentration of cellular fluid

Sol. Answer (4)

pH of blood and body fluids is maintained by these phosphate buffers.

8. Which element is/are found in cytochromes?

(1) Fe++ and Cu++ (2) Fe+++ and Mg++ (3) Mg++ (4) Cu++

Sol. Answer (1)

Cytochrome enzymes are rich in Fe2+ and Cu2+ centres.

9. The sweetest of all naturally occurring sugar is

(1) Glucose (2) Fructose (3) Mannose (4) Galactose

Sol. Answer (2)

Fructose is naturally sweetest sugar with high sweetening index.

10. Glucose is also called

(1) Dextrose (2) Corn sugar (3) Grape sugar (4) All of these

57Solutions of Assignment (Level-II) Biomolecules


Sol. Answer (4)

Glucose is found in abundance in maize/corn; grapes and is called dextrose as it rotates plane of polarised

light to right side.

11. Which of the following will yield only glucose on hydrolysis?

(1) Sucrose (2) Lactose (3) Maltose (4) Raffinose

Sol. Answer (3)

Sucrose = glucose + fructose

Maltose = glucose + glucose

Lactose = glucose + galactose

Raffinose = glucose + galactose + fructose

12. Cellulose is

(1) Heptopolysaccharide (2) Heteropolysaccharide, branched

(3) Hexosan polysaccharide, unbranched (4) Pentosan polysaccharide, branched

Sol. Answer (3)

Cellulose is a polymer of 6C glucose therefore called hexosan polysaccharide. It is an unbranched polymer.

13. Glucose is stored as glycogen in

(1) Pancreas (2) Bone

(3) Kidney (4) Liver

Sol. Answer (4)

Glucose is stored as glycogen in liver and muscles.

14. The number of monosaccharide units in a polysaccharide is

(1) 2 (2) 7

(3) 9 (4) More than 10

Sol. Answer (4)

More than 10 monosaccharides join together to form polysaccharides.

15. A cellulose molecule is formed by the polymerisation of glucose. The number of glucose molecules presentin a cellulose is

(1) 600 (2) 6000 (3) 60,000 (4) 60

Sol. Answer (2)

A cellulose molecule is formed by polymerisation of 6000 molecules of glucose.

(Protein, Lipids and Nucleic acids)

16. The structure of protein which gives a three dimensional view is

(1) Primary structure (2) -helix

(3) -pleated sheet (4) Tertiary structure

Sol. Answer (4)

Tertiary structure of protein gives a three dimensional view.



17. The product of the given reaction would be a

CH OH2

CH OH2

CHOH +

HOOC–R1

HOOC–R3

HOOC–R2

Glycerol Fatty acid

(1) Monoglyceride (2) Diglyceride

(3) Triglyceride (4) Both (1) & (3)

Sol. Answer (3)

The given structure has three fatty acids.

18. The given fatty acid is known as CH3(CH

2)7 CH = CH (CH

2)7 COOH

(1) Palmitic acid (2) Oleic acid

(3) Stearic acid (4) Arachidonic acid

Sol. Answer (2)

(CH3)2(CH

2)7CH = CH(CH

2)7COOH – Oleic acid

CH3(CH

2)14

COOH – Palmitic acid

CH3(CH

2)16

COOH – Stearic acid

Arachidonic acid : CH3(CH

2)4CH = CHCH

2CH = CHCH

2CH = CHCH

2CH = CH(CH

2)3COOH

(20 C)

19. Nucleic acids exhibit

(1) Secondary structure (2) Tertiary structure

(3) Quaternary structure (4) Both (2) & (3)

Sol. Answer (1)

Nucleic acid (DNA) has double helical structure and it exhibits secondary structure.

20. The backbone of a DNA molecule is made up of

(1) Adenine and guanine (2) Sugar-phosphate-sugar chain

(3) Cytosine and thymine (4) All of these

Sol. Answer (2)

Backbone of a DNA molecule is made up of Sugar – Phosphate – Sugar chain

SS

SS

P P

A T

G C

T A

3'

5' 3'

5'

SS

P P

P

P

P = PhosphateS = SugarA = AdenineT = ThymineG = GuanineC = Cytosine



21. If the sequence of bases in one of the DNA strand is A G G A G A A, then the sequence of bases in the othercomplementary strand of DNA would be

(1) C C T T C T T (2) T C T C T C C (3) T C C T C T T (4) C C T C T C T

Sol. Answer (3)

Because A = T, G C

22. RNA is a polymer of

(1) Ribonucleotides (2) Deoxyribonucleotides

(3) Deoxyribonucleosides (4) Ribonucleosides

Sol. Answer (1)

It is made up of ribose sugar, phosphate and nitrogenous bases (A, U, G, C).

23. t-RNA constitutes about

(1) 70-80% of the total RNA (2) 15% of the total RNA

(3) 5% of the total RNA (4) 1-3% of the total RNA

Sol. Answer (2)

r-RNA 70 – 80% of total RNA

t-RNA 15% of total RNA

m-RNA 2–5% of total RNA

24. In DNA, cytosine pairs with

(1) Guanine (2) Thymine (3) Adenine (4) Uracil

Sol. Answer (1)

A = T (2 hydrogen bonds between adenine and thymine)

G C (3 hydrogen bonds between cytosine and guanine)

25. Essential oils are those which are

(1) Essential for plants themselves (2) Always found only in animal products like butter

(3) Never used in soaps and cosmetics (4) A source of perfumes

Sol. Answer (4)

Essential oils are useful in making perfumes, cosmetics, skin care and dental pain relief.

26. Waxes are simple lipids formed by the combination of long chain fatty acid with long chain monohydric alcohol.Bees wax is made up of

(1) Palmitic and mericyl alcohol (2) Hexacosyl palmitate

(3) Ergosterol (4) Both (1) & (2)

Sol. Answer (4)

Bees wax is composed of 16 C (Hexacosanoic acid) and palmitic acid (16 C, saturated fatty acid) Mericylpalmitate is also found in bees wax.

27. An antifertility steroid is

(1) Diosgenin (2) Cortisol (3) Estradiol (4) Progesterone

Sol. Answer (1)

Diosgenin is produced by yam plant (Dioscorea) and is promoted as natural alternative to estrogen therapy.



28. Highest level of structural organisation present in Keratin of hair is

(1) Tertiary structure of protein (2) -helical structure of protein

(3) -pleated structure (4) Primary structure of protein

Sol. Answer (2)

-helical structure is found in keratin of hair, while -structure is found in fibroin of silk.

29. Casein of milk is

(1) Glycoprotein (2) Phosphoprotein (3) Chromoprotein (4) Metaloprotein

Sol. Answer (2)

Casein is a conjugated phosphoprotein found in milk.

30. The backbone of a nucleic acid strand is made up of

(1) Base and phosphate

(2) Sugar and phosphate

(3) Sugar and base

(4) Sugar, base and phosphate

Sol. Answer (2)

The backbone of a nucleic acid is made up of phosphodiester bond between sugar and phosphate.

31. Which of the following is not present in DNA?

(1) Cytosine (2) Adenine

(3) Guanine (4) Thiamine

Sol. Answer (4)

Thiamine is vitamin-B, while thymine is a nitrogenous base found in DNA.

32. What should be added to a nucleoside to yield a nucleotide?

(1) Sugar (2) Phosphoric acid

(3) Nitrogenous base (4) Sugar and nitrogenous base

Sol. Answer (2)

Nucleotide = Sugar + Nitrogenous Base + Phosphate

Nucleoside

33. Which of the following RNA is a carrier that delivers the correct amino acid for protein synthesis?

(1) m-RNA (2) r-RNA

(3) hn-RNA (4) t-RNA

Sol. Answer (4)

Transfer RNA (tRNA) brings the correct amino acid corresponding to codon on mRNA.

34. The two strands of DNA are coiled around

(1) Each other (2) Differently

(3) A common axis (4) Different axis

Sol. Answer (3)

The two strands of DNA are held at constant distance of 20 Å.



35. The two strands of DNA are held together by bonds of

(1) Nitrogen (2) Oxygen (3) Hydrogen (4) Carbon

Sol. Answer (3)

The strands of DNA are held together by hydrogen bond.

A = T, G CHydrogen bond

(Amino acid and Dynamic state of body contituents, Concept of metabolism)

36. The given amino acid is _______ in nature.

H N–C–H2

COOH

CH .COOH2

(1) Acidic (2) Basic (3) Neutral (4) Aromatic

Sol. Answer (1)

Given structure has an extra carboxylic group.

37. Which of the following are basic amino acids?

(1) Glycine and Alanine (2) Lysine and Arginine

(3) Glutamic acid and Aspartic acid (4) Histidine and Proline

Sol. Answer (2)

Lysine and Arginine Basic amino acid +ve charged

Glutamic acid and Aspartic acid Acidic amino acid –ve charge

38. Which of the following amino acids is involved in the formation of Heme?

(1) Tryptophan (2) Tyrosine (3) Glycine (4) Histidine

Sol. Answer (3)

Amino acid glycine provides nitrogen and carbon atoms for the synthesis of heme.

39. Which one of the following is alcoholic amino acid pair?

(1) Glycine and serine (2) Threonine and serine

(3) Phenylalanine and tyrosine (4) Tryptophan and glutamic acid

Sol. Answer (2)

These two amino acids contain alcohol group.

40. Lysine is an essential amino acid because

(1) It is very rare

(2) It has a high nutritive value

(3) It is an important constituent of all proteins

(4) It is not formed in the body and has to be provided through diet

Sol. Answer (4)

Essential amino acids are not synthesised in body.



41. In which of the following energy is released?

(1) Conversion of glucose into pyruvate (2) Formation of proteins from amino acids

(3) Conversion of glucose into lactic acid (4) Both (1) & (3)

Sol. Answer (4)

Anaerobic combustion of glucose releases energy in the form of ATP.

42. Adenosine Triphosphate (ATP) liberates high energy by the breakdown of

(1) Glycosidic bond (2) Hydrogen bond

(3) Phosphate bond (4) Both (1) & (3)

Sol. Answer (3)

ATP ADP + iP (inorganic phosphate)

43. Which of the following are basic amino acids?

(1) Glycine and Alanine

(2) Lysine and Arginine

(3) Glutamic acid and Aspartic acid

(4) Histidine and Proline

Sol. Answer (2)

Basic amino acid : Lysine and arginine

Acidic amino acid : Glutamate and Aspartate

44. One of the following amino acid or structure that does not contain sulphur is

(1) Tryptophan (2) Methionine

(3) Cystine (4) Cysteine

Sol. Answer (1)

Sulphur containing amino acid are cysteine and methionine

Cystine is formed upon joining two cysteine residues with a disulfide bond.

(The Living State, Enzymes)

45. Which of the following statements is correct?

(1) Biocatalysts accelerate the rate of a given metabolic reaction

(2) Biocatalysts are generally protein

(3) Enzyme catalysts differ from inorganic catalysts

(4) All of these

Sol. Answer (4)

46. Which of the following statements is incorrect w.r.t. inorganic catalysts?

(1) They do not occur in living cells (2) They are not specific for any reaction

(3) They get damaged at high temperature (4) They work efficiently at high pressure

Sol. Answer (3)

Inorganic catalyst work efficiently at high temperature and pressure, but enzyme get damaged at hightemperature (i.e. above 40ºC) except thermophillic enzyme.



47. Enzymes catalyse biochemical reactions by

(1) Lowering the activation energy (2) Increasing the activation energy

(3) Establishing stable bonds with substrate (4) Increasing temperature

Sol. Answer (1)

Enzyme lowers the activation energy and thus increases the rate of reaction.

48. Read the following :

(a) Low temperature preserves the enzyme

(b) Enzyme activity increases above optimum temperature

(c) Enzyme gets denatured at high temperature

(d) Competitive inhibitor competes with the product formed

Which of the following statement(s) are true?

(1) (a) & (c) (2) (b) & (d) (3) (c) & (d) (4) (a) & (b)

Sol. Answer (1)

(b) Statement is wrong because enzyme activity decreases above optimum temperature.

(d) Statement is wrong because competitive inhibitor completes with substrate for active site, not with productformed.

49. Enzymes catalysing the breakdown of larger molecules into smaller molecules are

(1) Hydrolases (2) Isomerases (3) Ligase (4) Both (1) & (3)

Sol. Answer (1)

Hydrolases are the enzyme which catalyse the breakdown of larger molecules into smaller molecules withthe addition of water.

Isomerases : They are the enzymes which catalyse the rearrangement of molecular structure to form isomers.

Ligases : They help in joining C – O, C – S, C – N etc. bonds by using energy of ATP.

50. Michaelis constant (Km

) value of enzyme is substrate concentration at which velocity of reaction is

(1) Vmax

(2) One third Vmax

(3) Half Vmax

(4) One fifth Vmax

Sol. Answer (3)

Vmax

Km

[s]

Vmax

2

Velocityof reaction

51. _______ catalyses covalent bonding of two substrates.

(1) Invertase (2) Amylase

(3) Glutamate pyruvate transaminase (4) PEP carboxylase

Sol. Answer (4)

This is a ligase enzyme.



52. The enzyme that catalyses the conversion of glucose-6-phosphate into fructose-6-phosphate is

(1) A ligase (2) An isomerase

(3) A lyase (4) A hydrolase

Sol. Answer (2)

Glucose-6-phosphate isomerase

��⇀↽�� fructose-6-phosphate

53. Study the following statements :

(a) The substrate binds to the active site of the enzyme

(b) Enzymes isolated from thermophilic organisms get denatured at 50°C

(c) The active site of enzyme breaks the chemical bonds of the product

(d) Prosthetic groups are tightly bound to the apoenzyme

Select the option which includes all correct statements :

(1) (a) & (c) (2) (c) & (d) (3) (b) & (c) (4) (a) & (d)

Sol. Answer (4)

(b) Statement is wrong, because thermophillic enzymes don't get denatured at high temperature, they workefficiently at high temperature (750ºC).

(c) Statement is wrong, because enzyme don't break chemical bonds of product but of substrate.

54. All enzymes are proteins, except

(1) Trypsin (2) Pepsin

(3) Steapsin (4) Ribozyme and Ribonuclease-P

Sol. Answer (4)

All enzymes are proteins, except, ribozyme and ribonuclease-P, which are RNA act as enzyme.

55. Cyanide kills an animal by

(1) Killing the brain cells

(2) Competitive inhibitor of enzyme cytochrome oxidise

(3) Inhibiting cytochrome oxidase, a mitochondrial enzyme essential for cellular respiration by Non-competitiveinhibition

(4) Killing the cells of cardiac muscles

Sol. Answer (3)

Cyanide poisoining is an example of non competitive inhibition of enzyme.

56. Electron transferring enzymes belong to

(1) Transferases (2) Oxidoreductases

(3) Lyases (4) Isomerases

Sol. Answer (2)

The main enzymes of electron transport chain are dehydrogenase, reductase, cytochrome oxidase, whichbelongs to the oxidoreductase class of an enzyme.

57. Enzymes are different from inorganic catalysts in

(1) Not being used up in reactions (2) Being proteinaceous in nature

(3) Having a high diffusion rate (4) Working at high temperature

Sol. Answer (2)

Enzymes are biomolecules that are proteins of RNA in nature.



58. What structural level enables the monomeric proteins to function as enzymes?

(1) Primary level (2) Secondary level

(3) Tertiary level (4) Quarternary level

Sol. Answer (3)

Highest level of organisation for monomeric protein is tertiary level when active site is formed.

59. A specific low molecular weight substance such as the product of another enzyme in the chain reaction whichbinds with a specific site of the enzyme different from its substrate binding site is called

(1) Competitive inhibitor

(2) Non-competitive inhibitor

(3) Irreversible inhibitor

(4) Allosteric modulator

Sol. Answer (4)

Allosteric enzyme have catalytic site where substrate binds and modulatory site where inhibitor or stimulatorcan bind.

60. The term feedback refers to

(1) The effect of substrate on the rate of enzyme action

(2) The effect of end products on the rate of enzymatic action

(3) The effect of enzyme concentration on its rate of action

(4) The effect of an external compound on the rate of enzymatic action

Sol. Answer (2)

When the product governs its own rate of formation is called ''feedback''.

61. Alcohol dehydrogenase enzyme also exists as isoenzyme. The number of isoenzyme forms of alcoholdehydrogenase in maize are

(1) 16 (2) 4 (3) 100 (4) 5

Sol. Answer (2)

Alcohol dehydrogenase has 4 isoenzymes in maize.

62. Which of the following is the best evidence for the lock and key theory of enzyme action ?

(1) All isolated enzymes have been identified as protein

(2) Compounds similar in structure to the substrate inhibit the reaction

(3) Enzymes are found in living organisms and speed up certain reaction

(4) Enzymes determine the direction of a reaction

Sol. Answer (2)

In lock and key hypothesis, the substrate and inhibitor show structural similarity.

63. Co-enzyme is

(1) Always a protein (2) Often a metal

(3) Always an inorganic compound (4) Often a vitamin

Sol. Answer (4)

Co-enzyme is loosely attached organic co-factor and often a vitamin B2 (Riboflavin) and vitamin B

3 (niacin).



SECTION - B

Previous Years Questions

1. The two functional groups characteristic of sugars are [NEET-2018]

(1) Hydroxyl and methyl (2) Carbonyl and methyl

(3) Carbonyl and hydroxyl (4) Carbonyl and phosphate

Sol. Answer (3)

Sugar is a common term used to denote carbohydrate.

Carbohydrates are polyhydroxy aldehyde, ketone or their derivatives, which means they have carbonyl andhydroxyl groups.

2. Which of the following are not polymeric? [NEET-2017]

(1) Nucleic acids (2) Proteins (3) Polysaccharides (4) Lipids

Sol. Answer (4)

– Nucleic acids are polymers of nucleotides

– Proteins are polymers of amino acids

– Polysaccharides are polymers of monosaccharides

– Lipids are the esters of fatty acids and alcohol

3. Which one of the following statements is correct, with reference to enzymes? [NEET-2017]

(1) Apoenzyme = Holoenzyme + Coenzyme (2) Holoenzyme = Apoenzyme + Coenzyme

(3) Coenzyme = Apoenzyme + Holoenzyme (4) Holoenzyme = Coenzyme + Cofactor

Sol. Answer (2)

Holoenzyme is conjugated enzyme in which protein part is apoenzyme while non-protein is cofactor.

Coenzyme are also organic compounds but their association with apoenzyme is only transient and serve ascofactors.

4. A non-proteinaceous enzyme is [NEET(Phase-2) 2016]

(1) Lysozyme (2) Ribozyme (3) Ligase (4) Deoxyribonuclease

Sol. Answer (2)

Ribozyme is RNA acting like an enzyme or biocatalyst.

5. Which of the following is the least likely to be involved in stabilizing the three-dimensional folding of mostproteins? [NEET(Phase-2) 2016]

(1) Hydrogen bonds (2) Electrostatic interaction

(3) Hydrophobic interaction (4) Ester bonds

Sol. Answer (4)

Ester bond is formed between sugar and phosphate in a nucleotide.

6. Which of the following describes the given graph correctly? [NEET(Phase-2) 2016]

Reaction

Substrate

Pote

ntial E

nerg

y

A

B

Product



(1) Endothermic reaction with energy A in presence of enzyme and B in absence of enzyme

(2) Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme

(3) Endothermic reaction with energy A in absence of enzyme and B in presence of enzyme

(4) Exothermic reaction with energy A in absence of enzyme and B in presence of enzyme

Sol. Answer (2)

Potential energy of substrate is more than the product. So it is an exothermic reaction. 'A' represents theactivation energy in the presence of enzyme while 'B' in the absence of enzyme i.e., enzyme lowers downthe activation energy.

7. A typical fat molecule is made up of [NEET-2016]

(1) Three glycerol and three fatty acid molecules

(2) Three glycerol molecules and one fatty acid molecule

(3) One glycerol and three fatty acid molecules

(4) One glycerol and one fatty acid molecule

Sol. Answer (3)

A typical fat molecule is triglyceride formed by esterification of one glycerol and three fatty acid molecules.

8. Which one of the following statements is wrong? [NEET-2016]

(1) Glycine is a sulphur containing amino acid (2) Sucrose is a disaccharide

(3) Cellulose is a polysaccharide (4) Uracil is a pyrimidine

Sol. Answer (1)

Glycine is simplest amino acid in which 'R' is replaced by H(Hydrogen).

9. Which of the following biomolecules does have a phosphodiester bond? [Re-AIPMT-2015]

(1) Nucleic acids in a nucleotide (2) Fatty acids in a diglyceride

(3) Monosaccharides in a polysaccharide (4) Amino acids in a polypeptide

Sol. Answer (1)

Phosphodiester bond is formed between two nucleotides of nucleic acid.

10. The chitinous exoskeleton of arthropods is formed by the polymerisation of [Re-AIPMT-2015]

(1) Lipoglycans (2) Keratin sulphate and chondroitin sulphate

(3) D-glucosamine (4) N-acetyl glucosamine

Sol. Answer (4)

Exoskeleton of arthropods is made up of chitin. Chitin is a homopolymer of N-acetyl glucosamine.

11. Which one of the following is not applicable to RNA? [Re-AIPMT-2015]

(1) Chargaff's rule (2) Complementary base pairing

(3) 5' phosphoryl and 3' hydroxyl ends (4) Heterocyclic nitrogenous bases

Sol. Answer (1)

Chargaff's rule is applicable only for dsDNA.

12. In sea urchin DNA, which is double stranded 17% of the bases were shown to be cytosine. The percentagesof the other three bases expected to be present in this DNA are [AIPMT-2015]

(1) G 8.5%, A 50%, T 24.5% (2) G 34%, A 24.5%, T 24.5%

(3) G 17%, A 16.5%, T 32.5% (4) G 17%, A 33%, T 33%

Sol. Answer (4)

According to Chargaff’s rule, [A] = [T] and [C] = [G]

Given, [C] = 17%, and [A] = 33%, [T] = 33%.



13. Which one of the following statements is incorrect? [AIPMT-2015]

(1) The presence of the competitive inhibitor decreases the Km of the enzyme for the substrate

(2) A competitive inhibitor reacts reversibly with the enzyme to form an enzyme-inhibitor complex

(3) In competitive inhibition, the inhibitor molecule is not chemically changed by the enzyme

(4) The competitive inhibitor does not affect the rate of breakdown of the enzyme-substrate complex

Sol. Answer (1)

The presence of competitive inhibitor increases Km value of enzymes

14. Select the option which is not correct with respect to enzyme action: [AIPMT-2014]

(1) Substrate binds with enzyme at its active site

(2) Addition of lot of succinate does not reverse the inhibition of succinic dehydrogenase by malonate

(3) A non - competitive inhibitor binds the enzyme at a site distinct from that which binds the substrate

(4) Malonate is a competitive inhibitor of succinic dehydrogenase

Sol. Answer (2)

Inhibition of succinic dehydrogenase by malonate is an example of competitive inhibition. This is reversiblereaction. On increasing the substrate (succinate) concentration the effect of inhibitor is removed and V

max

remains the same.

15. Which one of the following is a non - reducing carbohydrate? [AIPMT-2014]

(1) Maltose (2) Sucrose (3) Lactose (4) Ribose 5-phosphate

Sol. Answer (2)

Lactose, Maltose, Ribose 5-phosphate all are reducing sugars.

16. A phosphoglyceride is always made up of: [NEET-2013]

(1) Only an unsaturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached

(2) A saturated or unsaturated fatty acid esterified to a glycerol molecule to which a phosphate group is alsoattached

(3) A saturated or unsaturated fatty acid esterified to a phosphate group which is also attached to a glycerolmolecule

(4) Only a saturated fatty acid esterified to a glycerol molecule to which a phosphate group is also attached

Sol. Answer (2)

17. The essential chemical components of many coenzymes are: [NEET-2013]

(1) Nucleic acids (2) Carbohydrates (3) Vitamins (4) Proteins

Sol. Answer (3)

Niacin and riboflavin are used as coenzymes in NAD and FAD respectively.

18. Transition state structure of the substrate formed during an enzymatic reaction is : [NEET-2013]

(1) Permanent but unstable (2) Transient and unstable

(3) Permanent and stable (4) Transient but stable

Sol. Answer (2)

Transition state is a temporary structure formed during an enzymatic reaction.

19. Macromolecule chitin is [NEET-2013]

(1) Phosphorus containing polysaccharide (2) Sulphur containing polysaccharide

(3) Simple polysaccharide (4) Nitrogen containing polysaccharide

Sol. Answer (4)

Chitin is a polymer of N-acetyl glucosamine.



20. Which one out of A – D given below correctly represents the structural formula of the basic amino acid?

NH

|C|CH

|CH

|C

2

2

2

OHO

H COOH

A B C D

NH

|C|CH

|OH

2

2

H COOH

CH OH

|CH

|CH

|NH

2

2

2

2

NH2

C

CH2

|CH

2

|CH

2

|CH

2

|NH

2

H COOH

[AIPMT (Prelims)-2012]

(1) A (2) B (3) C (4) D

Sol. Answer (4)

'D', option has an extra amino group, because of which it carry +ve charge which comes under basic aminoacid.

21. Given below is the diagrammatic representation of one of the categories of small molecular weight organic compoundsin the living tissues. Identify the category shown and the one blank component “X” in it

OHOCH2

"X"

OH OH

[AIPMT (Prelims)-2012]

Category Component

(1) Nucleotide Adenine

(2) Nucleoside Uracil

(3) Cholesterol Guanine

(4) Amino acid NH2

Sol. Answer (2)

The given structure doesn't have a phosphate group, so it is nucleoside and "X" is uracil because is ribosesugar.

22. For its activity, carboxypeptidase requires [AIPMT (Mains)-2012]

(1) Copper (2) Zinc (3) Iron (4) Niacin

Sol. Answer (2)

Carboxypeptidase requires Zn2+ metal ion.

23. Which one of the following biomolecules is correctly characterised? [AIPMT (Mains)-2012]

(1) Alanine amino acid – Contains an amino group and an acidic group anywhere in the molecule

(2) Lecithin – a phosphorylated glyceride found in cell membrane

(3) Palmitic acid – an unsaturated fatty acid with 18 carbon atoms

(4) Adenylic acid – adenosine with a glucose phosphate molecule

Sol. Answer (2)

Option (1) is wrong, because alanine contains an amino group and an acidic group at -carbon in the molecule.

Option (3) is wrong, because palmitic acid is a saturated fatty acid with 16C atoms.

Option (4) is wrong, because adenylic acid is form by adding phosphate group to adenosine.



24. The curve given below show enzymatic activity with relation to three conditions (pH, temperature and substrateconcentration)

y-axis

x-axis

What do the two axes (x and y) represent? [AIPMT (Prelims)-2011]

x-axis y-axis

(1) Enzymatic activity Temperature

(2) Enzymatic activity pH

(3) Temperature Enzyme activity

(4) Substrate concentration Enzymatic activity

Sol. Answer (3)

x

y

pH or Temperature

Enzymatic activity

25. Which one of the following structural formulae of two organic compound is correctly identified along with itsrelated function

R —C—O—CH2

CH —O—C—R2

CH —O—P—O—CH —CH2 22

O

O

O

OH N

CH3CH

3

CH3

A

+ NH

N

NH2

N

N

B[AIPMT (Prelims)-2011]

(1) A : Lecithin – a component of cell membrane

(2) B : Adenine – a nucleotide that makes up nucleic acids

(3) A : Triglyceride – major source of energy

(4) B : Uracil – a component of DNA

Sol. Answer (1)

Given structure 'A' is Lecithin and 'B' is Adenine.

26. The figure given below shows the conversion of a substrate into product by an enzyme. In which one of thefour options (1–4) the components of reaction labelled as A, B, C and D are identified correctly?

B Substrate

Product

Progress of Reaction

C

D

A

[AIPMT (Mains)-2010]



A B C D

(1) Potential energy Transit ion state Activation energy with

enzyme

Activation energy

without enzyme

(2) Transit ion state Potential energy Activation energy

without enzyme

Activation energy with

enzyme

(3) Activation energy without enzyme

Transit ion state Activation energy with enzyme

Potential energy

(4) Activation energy with enzyme

Transit ion state Activation energy without enzyme

Potential energy

Sol. Answer (2)

27. Three of the following statements about enzymes are correct and one is wrong. Which one is wrong?

[AIPMT (Mains)-2010]

(1) Enzymes require optimum pH for maximal activity

(2) Enzymes are denatured at high temperature but in certain exceptional organisms they are effective evenat temperatures 80°-90°C

(3) Enzymes are highly specific

(4) Most enzymes are proteins but some are lipids

Sol. Answer (4)

Most enzymes are protein but some are RNA i.e. Ribonuclease-P and ribozyme.

28. Which one of the following pairs is wrongly matched? [AIPMT (Prelims)-2009]

(1) Alcohol – Nitrogenase

(2) Fruit juice – Pectinase

(3) Textile – Amylase

(4) Detergents – Lipase

Sol. Answer (1)

Nitrogenase is useful in fixation of nitrogen.

29. Carbohydrates are commonly found as starch in plant storage organs. Which of the following five propertiesof starch (a - e) make it useful as a storage material? [AIPMT (Prelims)-2008]

a. Easily translocated b. Chemical non-reactive

c. Easily digested by animals d. Osmotically inactive

e. Synthesized during photosynthesis

The useful properties are

(1) Both a & e

(2) Both b & c

(3) Both b & d

(4) a, c & e

Sol. Answer (3)

Carbohydrates like glycogen and starch are relatively easy to store because of the following advantages.

They are stored in bulk.

They are chemically non-reactive.

They are osmotically inactive.



30. An organic substance bound to an enzyme and essential for its activity is called [AIPMT (Prelims)-2006]

(1) Coenzyme (2) Holoenzyme

(3) Apoenzyme (4) Isoenzyme

Sol. Answer (1)

Organic compound which bound to an enzyme is either coenzyme or prosthetic group.

31. Telomerase is an enzyme which is a : [AIPMT (Prelims)-2005]

(1) Repetitive DNA (2) RNA

(3) Simple protein (4) Ribonucleoprotein

Sol. Answer (4)

32. Which of the following is the simplest amino acid? [AIPMT (Prelims)-2005]

(1) Tyrosine (2) Asparagine (3) Glycine (4) Alanine

Sol. Answer (3)

In glycine, the R-group is replaced by hydrogen.

HOOC C

H

NH2

H = R group

33. Enzymes, vitamins and hormones can be classified into a single category of biological chemicals, because all ofthese [AIPMT (Prelims)-2005]

(1) Enhance oxidative metabolism

(2) Are conjugated proteins

(3) Are exclusively synthesized in the body of a living organism as at present

(4) Help in regulating metabolism

Sol. Answer (4)

(1) is incorrect, because enzymes can both enhance and inhibit the oxidative metabolism.

(3) is incorrect, different enzymes, vitamins and hormones are synthesized in the body at different situations.

(2) is incorrect, because all hormones and enzymes are not conjugated protein.

34. Carbohydrates, the most abundant biomolecules on earth, are produced by [AIPMT (Prelims)-2005]

(1) All bacteria, fungi and algae (2) Fungi, algae and green plant cells

(3) Some bacteria, algae and green plant cells (4) Viruses, fungi and bacteria

Sol. Answer (3)

Autotrophic organism produce glucose by photosynthesis which is a carbohydrate. Heterotrophies are dependenton autotrophs and don't produce carbohydrates and fungi are saprobic organisms.

35. Which of the following statements regarding enzyme inhibition is correct ? [AIPMT (Prelims)-2005]

(1) Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate

(2) Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein

(3) Competitive inhibition is seen when the substrate and the inhibitor compete

(4) Non-competitive inhibitors often bind to the enzyme irreversibly



Sol. Answer (3)

(1) is wrong, because competitive inhibition of an enzyme can be overcome by adding large amount ofsubstrate.

(2) is wrong, because competitive inhibtion is seen when a substrate competes with an inhibitor for bindingto the active site of enzyme.

(4) is wrong, because non-competitive inhibitor often bind to enzyme irreversibly.

36. The catalytic efficiency of two different enzymes can be compared by the [AIPMT (Prelims)-2005]

(1) The Km value (2) The pH optimum value

(3) Formation of the product (4) Molecular size of the enzyme

Sol. Answer (1)

Enzymes with low Km are considered as good enzymes due to their high affinity for substrates.

37. The four elements that make up 96% of all the elements found in a living system are

(1) C, H, O and P (2) C, N, O and P (3) H, O, C and N (4) C, H, O and S

Sol. Answer (3)

% weight of human body : C = 18.5; O = 65.0; N = 3.3; H = 0.5

38. High cholesterol patients are advised to use

(1) Ghee, butter and oils (2) Groundnut oil, margarine and vegetable oils

(3) Fatty oil and butter (4) Cheese, dalda and ghee

Sol. Answer (2)

These oils contain polyunsaturated fatty acids (i.e. more than one double bond) and they are usuallyrecommended by doctors to person having hypertension, high blood cholesterol and other cardiovasculardiseases.

39. Essential amino acid is

(1) Phenylalanine (2) Glycine (3) Aspartic acid (4) Serine

Sol. Answer (1)

Essential amino acids are leucine, isoleucine, valine, tryptophane, phenylalanine, lysine and methionine.

40. Lipids are insoluble in water because lipid molecules are

(1) Hydrophilic (2) Hydrophobic (3) Neutral (4) Zwitter ions

Sol. Answer (2)

Hydro-means water, phobic - means repeling or hating

Lipids are hydrophobic that's why they are not soluble in water.

41. The major role of minor elements inside living organisms is to act as

(1) Co-factors of enzymes

(2) Building blocks of important amino acids

(3) Constituents of hormones

(4) Binders of cell structure

Sol. Answer (1)

Minor elements basically includes Zn, Mg, K, Ni, Co, NAD+, NADP+, they all come under the category ofcofactor.



42. Nucleotides are building blocks of nucleic acids. Each nucleotide is a composite molecule formed by

(1) Base-sugar-phosphate (2) Base-sugar-OH

(3) (Base-sugar-phosphate)n

(4) Sugar-phosphate

Sol. Answer (1)

Nucleotide : Base + Sugar + Phosphate

Nucleic acid : (Base + Sugar + Phosphate)n

43. About 98 percent of the mass of every living organism is composed of just six elements including carbon,hydrogen, nitrogen, oxygen and

(1) Sulphur and magnesium

(2) Magnesium and sodium

(3) Calcium and phosphorus

(4) Phosphorus and sulphur

Sol. Answer (3)

44. Which of the following is a neutral amino acid?

(1) Glutamine (2) Arginine (3) Valine (4) Asparagine

Sol. Answer (3)

Glutamine, Asparagine Amide group containing amino-acid.

Arginine Basic amino acid

45. The most unsaturated fatty acid is

(1) Linoleic acid (2) Oleic acid

(3) Linolenic acid (4) Arachidonic acid

Sol. Answer (4)

Arachidonic acid : It is 20 C containing unsaturated fattty acid (C20

H32

O2) with four double bond.

Oleic acid – 1 double bond

Linoleic acid – 2 double bonds

Linolenic acid – 3 double bonds

46. Which of the following is a nucleotide?

(1) Thymidine (2) Cytosine

(3) Thiamine (4) Uridylic acid

Sol. Answer (4)

Thymidine – Nucleoside; Thiamine – Vitamin; Cytosine – Nitrogen base; Uridylic acid – Nucleotide

47. Which of the following is incorrect regarding the amino acids and their functions?

(1) Tyrosine : Converted into epinephrine hormone and used in the synthesis of melanin pigment

(2) Glycine : Involved in the formation of heme

(3) Tryptophan : Helps in the synthesis of auxin hormone

(4) Histidine : Can be converted into histamine by the removal of amino group

Sol. Answer (4)

Histamine is derived from amino acid histidine through decarboxylation.



48. Which of the following is the diagrammatic representation of phospholipid lecithin?

(1)

CH – O – C – R2 1

CH – O – C – R2

O

CH – O – P – O – CH – CH – NH2 2 2 3

+

O

OH

O

(2)

CH – O – C – R2 1

CH – O – C – R2

O

CH – O – C – R2 3

O

O

(3)

CH – O – C – R2 1

CH – O – C – R2

O

CH – O – P – O – CH – CH – N – CH2 2 2 3

O

OH

O

CH3

CH3

+

(4)

CH – O – C – R2 1

R – C – O – 2

CH

O

CH – O – P – OH2

O

O

OH

Sol. Answer (3)

Lecithin is a phospholipid present in cell membrane

49. Which of the following is not a secondary metabolite of plant cell?

(1) Rubber (2) Chlorophyll (3) Essential oil (4) Tannins

Sol. Answer (2)

RubberPolymeric substance

Essential oil

Tannins Pigments

50. The most abundant molecule in cell is

(1) Water (2) Carbohydrate (3) Lipid (4) Protein

Sol. Answer (1)

Water = 70 – 90% of the total cellular mass

Carbohydrate = 3%

Lipid = 2%

Protein = 10–15%

51. Which are the most diverse molecules in the cell?

(1) Lipids (2) Mineral salts (3) Proteins (4) Carbohydrates

Sol. Answer (3)

Proteins are made up of 20 different amino acids and are heteropolymers of amino acids.

52. The most abundant organic compound on earth is

(1) Protein (2) Cellulose

(3) Lipids (4) Steroids

Sol. Answer (2)

Plant cell wall is made up of cellulose.



53. Haemoglobin is a type of

(1) Carbohydrate (2) Respiratory pigment (3) Vitamin (4) Skin pigment

Sol. Answer (2)

Because haemoglobin get binds to oxygen and help in the transportation of O2.

54. Collagen is

(1) Fibrous protein (2) Globular protein (3) Lipid (4) Carbohydrate

Sol. Answer (1)

Collagen is a thread like protein which is insoluble in water.

55. Maltose is formed of two molecules of

(1) Fructose (2) Lactose (3) Glucose (4) Sucrose

Sol. Answer (3)

Fructose = Monosaccharides

Lactose = Galactose + Glucose

Sucrose = Glucose + Fructose

Maltose = Glucose + Glucose

56. A polysaccharide which is synthesized and stored in liver cells is

(1) Arabinose (2) Glycogen (3) Lactose (4) Galactose

Sol. Answer (2)

Glycogen is a polymer of glucose.

57. Agar is commercially obtained from

(1) Red algae (2) Blue-green algae (3) Brown algae (4) Green algae

Sol. Answer (1)

Agar is a type of mucopolysaccharide and is obtained from red algae. It is used as culture medium inlaboratory.

58. Which of the following groups consists of polysaccharides only?

(1) Sucrose, glucose and fructose (2) Maltose, lactose and fructose

(3) Glycogen, sucrose and maltose (4) Glycogen, cellulose and starch

Sol. Answer (4)

Sucrose Disaccharide; Fructose Monosaccharide

Glucose Monosaccharide; Maltose Disaccharide

Lactose Disaccharide; Glycogen Polysaccharide

Cellulose Polysaccharide; Starch Polysaccharide

59. Lactose is composed of

(1) Glucose + galactose (2) Fructose + galactose

(3) Glucose + fructose (4) Glucose + glucose

Sol. Answer (1)

Lactose is a disaccharide.



60. Cellulose, the most important constituent of plant cell wall is made up of

(1) Branched chain of glucose molecules linked by 1, 4 glycosidic bond in straight chain and1, 6 glycosidic bond at the site of branching

(2) Unbranched chain of glucose molecules linked by 1, 4 glycosidic bond

(3) Branched chain of glucose molecules linked by 1, 6 glycosidic bond at the site of branching

(4) Unbranched chain of glucose molecules linked by 1, 4 glycosidic bond

Sol. Answer (2)

Glycogen and starch are branched polymer of glucose while cellulose is unbranched polymer of glucose.

61. A person is eating boiled potato. His food contains

(1) Cellulose, which can be digested by cellulase

(2) Starch, which cannot be digested

(3) Lactose, which cannot be digested

(4) DNA, which can be digested by pancreatic DNAase

Sol. Answer (4)

(1) is wrong, because our gut can't produce cellulose.

(2) is wrong because potato contain starch and it can be digested.

(3) is wrong, because lactose is absent in potato.

62. Which of the following is a reducing sugar?

(1) Galactose

(2) Gluconic acid

(3) -methyl galactoside

(4) Sucrose

Sol. Answer (1)

It can reduce Cu2+ ions into Cu+ ions.

63. An important step in the manufacture of pulp for paper industry is the

(1) Preparation of pure cellulose

(2) Treatment of wood with chemicals that break down cellulose

(3) Removal of oils present in the wood by treatment with suitable chemicals

(4) Removal of water from the wood by prolonged heating at approximately 50°C

Sol. Answer (1)

The raw material for paper is cellulose.

64. 1-4 linkages are present in

(1) Cellulose (2) Chitin

(3) Starch (4) Both (1) & (2)

Sol. Answer (4)

Cellulose – (1, 4) linkage (-glucose)

Chitin – (1, 4) linkage (N-acetyl glucosamine)

Starch – (1, 4) (in straight chain) of amylose and amylopectin

(1, 6) (at branching)



65. Which of the following statements is false?

(1) Cellulose is the most abundant organic compound in the biosphere

(2) Cellulose is an unbranched polymer with -1,4 glycosidic bonds

(3) Rayon and cellophane are chemically similar to cellulose xanthate

(4) Cellulose can be digested by the herbivores by -amylase, produced by the glandular cells of theiralimentary canal

Sol. Answer (4)

Cellulose can be digested by the herbivores because they have special type cellulose digesting micro-organismfor the digestion of cellulose.

66. If the total amount of adenine and thymine in a double-stranded DNA is 60%, the amount of guanine in thisDNA will be

(1) 15% (2) 20% (3) 30% (4) 40%

Sol. Answer (2)

A + T = 60%

Then, C + G = 40%, when 20% C and 20% = G

67. DNA has equal number of adenine and thymine residues (A = T) and equal number of guanine and cytosine(G = C). This relationship is known as

(1) Chargaff's rule (2) Coulomb's law

(3) Le Chatelier's principle (4) Van't Hoff plot

Sol. Answer (1)

68. Which of the following pairs of nitrogenous bases of nucleic acids is mismatched with the category mentionedagainst it?

(1) Adenine, Thymine – Purines (2) Thymine, Uracil – Pyrimidines

(3) Uracil, Cytosine – Pyrimidines (4) Guanine, Adenine – Purines

Sol. Answer (1)

Adenine and Guanine Purines

Thymine, uracil, cytosine Pyrimidines

69. In a DNA molecule

(1) There are two strands which run antiparallel-one in 5 3 direction and other in 3 5

(2) The total amount of purine nucleotides and pyrimidine nucleotides is not always equal

(3) There are two strands which run parallel in the 5 3 direction

(4) The proportion of adenine in relation to thymine varies with the organism

Sol. Answer (1)

In DNA, two antiparallel strands are coiled around a common axis.

70. Which purine base is found in RNA?

(1) Thymine (2) Uracil (3) Cytosine (4) Guanine

Sol. Answer (4)

Thymine present in DNA, not in RNA

Cytosine, uracil pyrimidines



71. Similarity in DNA and RNA is that

(1) Both are polymers of nucleotides

(2) Both have similar pyrimidines

(3) Both have similar sugar

(4) Both are genetic material in man

Sol. Answer (1)

Nucleotide is a monomeric unit of a nucleic acid.

72. Length of one loop of B-DNA is

(1) 3.4 nm

(2) 0.34 nm

(3) 20 nm

(4) 10 nm

Sol. Answer (1)

Pitch of B-DNA = 34 Å 3.4 nm (∵ 1 Å = 0.1 nm)

73. Which of the following enzymes is used to join bits of DNA?

(1) Ligase (2) Primase

(3) DNA polymerase (4) Endonuclease

Sol. Answer (1)

Class VI Ligase enzyme is used to join the bits of DNA.

Primase Is an enzyme use to attach primer.

DNA polymerase is an enzyme use to add nucleotide in template strand of DNA.

Endonuclease It is an restriction enzyme which causes internal cleavage of DNA.

74. The 3-5 phosphodiester linkages inside a polynucleotide chain serve to join

(1) One DNA strand with the other DNA strand

(2) One nucleoside with another nucleoside

(3) One nucleotide with another nucleotide

(4) One nitrogenous base with pentose sugar

Sol. Answer (3)

A nucleotide is a monomeric unit of nucleic acid which are joined together by 3' – 5' phosphodiester bonds.

75. ATP is

(1) Nucleotide

(2) Nucleoside

(3) Nucleic acid

(4) Vitamin

Sol. Answer (1)

ATP (Adenosine triphosphate) is made up of adenine, ribose sugar and 3 phosphate groups.



76. The role of an enzyme in a reaction is to/as

(1) Decrease activation energy

(2) Increase activation energy

(3) Inorganic catalyst

(4) None of these

Sol. Answer (1)

Substrate energy

Product

Progress of reaction

Potential energy

Transition state

Activation energy without enzyme

Activation energy with enzyme

77. Which of the following factor(s) do(es) not affect enzyme activity?

A. Temperature B. pH

C. Enzyme concentration D. Product concentration

E. Substrate concentration F. Activation energy

(1) C only (2) C & D (3) D only (4) F only

Sol. Answer (4)

Enzyme activity is affected by temperature, pH, enzyme concentration, product concentration and substrateconcentration.

Enzyme are not affected by activation energy but it lowers down the activation energy.

78. A competitive inhibitor of succinic dehydrogenase is

(1) Malate (2) Malonate

(3) Oxaloacetate (4) Both (2) & (3)

Sol. Answer (4)

Competitive inhibitors of succinic dehydrogenase are malate, malonate, oxaloacetate.

79. Which of the following is a typical example of ‘feedback inhibition’?

(1) Cyanide and cytochrome reaction

(2) Sulpha drugs and folic acid synthesizer bacteria

(3) Allosteric inhibition of hexokinase by glucose 6-phosphate

(4) Reaction between succinic dehydrogenase and succinic acid

Sol. Answer (3)

(1) Cyanide and cytochrome reaction Example of non-competitive inhibition.

(2) Sulpha drugs and folic acid synthesizer bacteria are example of non-competitive inhibition.

(4) Reaction between succinic dehydrogenase and succinic acid are example of competitive inhibition.



80. Which factor is responsible for inhibition of enzymatic process during feedback?

(1) Substrate

(2) Enzyme

(3) End product

(4) Temperature

Sol. Answer (3)

Feedback inhibition is also konwn as End product inhibition or allosteric modulation.

81. Which of the following is true for competitive enzyme inhibition?

(1) Decrease in Vmax

and Km

(2) Unchanged Vmax

and decrease in Km

(3) Unchanged Vmax

and increase in Km

(4) Increase in Vmax

and Km

Sol. Answer (3)

Vmax

= constant; Km

= increased

Vmax

Vmax

2

NoInhibitor

Km [S]

With inhibitor

Km'

Reaction velocity

82. The Michaelis constant Km is

(1) Numerically equal to ½ Vmax

(2) Dependent on the enzyme concentration

(3) Numerically equal to the substrate concentration that gives half maximal velocity

(4) Increased in the presence of non-competitive inhibitor

Sol. Answer (3)

vmax

Km

[s]

vmax

2

Velocityof reaction

83. If an enzyme has been given the EC code 5.2.1.7, it is likely to be involved in

(1) Digestion

(2) Redox reaction

(3) Isomerization

(4) Molecular breakdown

Sol. Answer (3)

EC code 5.2.1.7, in this the first digit represents class of enzyme.

And the class V of enzyme is isomerases, which catalyse the isomerisation reaction.



84. Prosthetic group is a part of holoenzyme. It is

(1) Loosely attached organic part

(2) Loosely attached inorganic part

(3) Non-protein organic part firmly attached with apoenzyme

(4) None of these

Sol. Answer (3)

Enzyme (Holoenzyme)

Protein(Apoenzyme)

Non-protein (Cofactor)

Inorganic compoundOrganic compound

Loosely bound(Coenzyme)

Tightly bound(Prosthetic group)

It includes metal ions

., Zn , Mg , etc.i.e2+ 2+

Ca2+

85. Which of the following has carbohydrate as prosthetic group?

(1) Glycoprotein

(2) Chromoprotein

(3) Lipoprotein

(4) Nucleoprotein

Sol. Answer (1)

It is a conjugated protein in which protein is conjugated with carbohydrate.

86. Mark the mismatched pair.

(1) Cellulose : Unbranched polymer with ,1-4 glycosidic linkage

(2) Cellophane : Cellulose xanthate

(3) Carboxypeptidase : Exopeptidase, Mg2+ acts as a co-factor

(4) Aminopeptidase : Exopeptidase, cleaves the peptide bond at N-terminal end

Sol. Answer (3)

Carboxypeptidase requires Zn2+ as cofactor.

87. Apoenzyme is

(1) Always a protein

(2) Often a metal

(3) Always an inorganic compound

(4) Often a vitamin

Sol. Answer (1)

Protein part of enzyme is known as apoenzyme and non-protein part of enzyme is known as cofactor.



SECTION - C

Assertion-Reason Type Questions

1. A : Cofactor of an enzyme may be a prosthetic group.

R : NAD derived from niacin is a co-enzyme.

Sol. Answer (2)

Organic compound that firmly attaches to protein part of enzyme is prosthetic group.

2. A : Linolenic acid is an essential fatty acid.

R : Linolenic acid cannot be synthesised in human beings.

Sol. Answer (1)

PUFA (Polyunsaturated Fatty Acids) are essential fatty acid.

3. A : Hormones are not enzymes, but they can stimulate the release of enzymes.

R : Hormones are used up in metabolism, but enzymes can act over and over again.

Sol. Answer (2)

Enzymes are not used up in metabolism.

4. A : Tertiary structure of protein molecules makes them biologically active.

R : It is native configuration of protein molecules maintained by multiple covalent bonds only.

Sol. Answer (3)

Enzymes exist in tertiary structure in which side groups come close and form the active site.

5. A : Dextrins are intermediate polysaccharides formed during hydrolysis of starch into sugar.

R : Ascorbic acid is a sugar derivative.

Sol. Answer (2)

Ascorbic acid is a sugar acid.

6. A : Non-competitive inhibitors have no effect on Vmax

.

R : In non-competitive inhibition, inhibitor and substrate bind at same sites on the enzyme.

Sol. Answer (4)

Non-competitive inhibitors decrease Vmax

.

7. A : The polypeptide coil of collagen helix is strengthened by the estabilishment of hydrogen bond between >NH - group of glycine residue of each strand with –CO group of other two strand.

R : In collagen helix, locking effect also occurs with the help of proline and hydroxyproline amino acid.

Sol. Answer (2)

In collagen, there are three polypeptides that coil around one another.

8. A : Allosteric enzymes do not show a typical Michaelis Menten constant or behaviour.

R : All enzymes in human body work at same pH.

Sol. Answer (3)

Allosteric enzymes don't obey Michaelis Menten constant. Enzymes in human body work at different pH based

on their location.



9. A : amylase of wheat endosperm has 16 isoenzymes.

R : In competitive inhibition, Vmax

decreases.

Sol. Answer (3)

Isoenzymes are the isomeric forms of same enzyme.

10. A : Tertiary structure of protein is absolutely necessary for many biological activities of proteins.

R : In proteins, only right handed helices are observed.

Sol. Answer (2)

At tertiary structure of protein, active site of enzymes is formed.

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